Field of the Invention
The present invention relates to a method and a device for setting process parameters of a production process for an elongate sheet-like product to achieve a predeterminable product quality.
In production processes, in particular continuous processes for the production of elongate sheet-like products, for example rolled steel, it is necessary to set a large number of process parameters to suitable values in order to achieve a smooth production procedure and good quality of the product.
If for example the production of rolled steel is considered, taken by way of example as a particular area of application, of the present invention, it becomes evident that numerous production parameters have an influence on the final product. This begins with the metallurgical composition of the melt, with its treatment in the melting pan, continues with the parameters during the casting operation and the thermal profiles prevailing there and then relates in particular to the hot-rolling mill with many parameters such as rolling pressure, temperature of the strip etc. A large number of measured values in all stages of production serve for controlling the production parameters, it often needing decades of experience on the part of the operating personnel to keep a production process stable and achieve a desired quality of product in each case. In particular in the case of newly designed and newly constructed installations, it is often difficult to find out the correct production parameters for achieving a specific product quality.
Of course, it has always been possible to measure simple product characteristics such as width and thickness of the strip during the production process and to control them by changing production parameters decisive for these characteristics.
For sheet-like products, however, not only the dimensions and the composition of the material are significant but most particularly also the condition of the surface. While in the past it was not possible in practice, with a strip running at high speed, to inspect the surface continuously, detect defects and classify them, there have for some time been surface inspection systems based on cameras with downstream networked image analysis systems which make surface inspection possible even while a strip is running.
In particular, such surface inspection systems have been used in the past for quality control, i.e. these systems produced a kind of map of the surface of a steel strip, onto which observed defects could be entered with their position and also be classified according to type and frequency and, for example, periodicity. In this way, it was possible for finished rolls of sheet to be provided with quality certificates, providing information on the location, type and/or frequency of defects. Such a surface inspection system is described for example in DE 197 20 307 A1 or DE 197 30 622.
The surface maps were able to provide valuable information during subsequent inspection as to locations in the production process at which specific defects were caused, but this could neither be automated nor systemized.